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6 papers
Rank and order of a finite group admitting a Frobenius-like group of automorphisms
G. Ercana,
İ. Güloğlub,
E. I. Khukhrocd a Middle East Technical University, Ankara, Turkey
b Doğuş University, Istanbul, Turkey
c Sobolev Institute of Mathematics, pr. Akad. Koptyuga 4, Novosibirsk, 630090, Russia
d University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK
Abstract:
A finite group
$FH$ is said to be Frobenius-like if it has a nontrivial nilpotent normal subgroup
$F$ with a nontrivial complement
$H$ such that
$FH/[F,F]$ is a Frobenius group with Frobenius kernel
$F/[F,F]$. Suppose that a finite group
$G$ admits a Frobenius-like group of automorphisms
$FH$ of coprime order with certain additional restrictions (which are satisfied, in particular, if either
$|FH|$ is odd or
$|H|=2$). In the case where
$G$ is a finite
$p$-group such that
$G=[G,F]$ it is proved that the rank of
$G$ is bounded above in terms of
$|H|$ and the rank of the fixed-point subgroup
$C_G(H)$, and that
$|G|$ is bounded above in terms of
$|H|$ and
$|C_G(H)|$. As a corollary, in the case where
$G$ is an arbitrary finite group estimates are obtained of the form
$|G|\le|C_G(F)|\cdot f(|H|,|C_G(H)|)$ for the order, and $\mathbf r(G)\le\mathbf r(C_G(F))+g(|H|,\mathbf r(C_G(H)))$ for the rank, where f and g are some functions of two variables.
Keywords:
automorphism, finite group, Frobenius group, rank, order.
UDC:
512.542 Received: 24.02.2014